When it comes to selling weapons, the United States is in a league of its own: more than 40 percent of all arms sold worldwide come from US companies. Five corporations, known as the “big five,” dominate that trade – and since the start of the wars in Gaza and Ukraine, their revenues have soared. But selling weapons overseas is only part of their business. At home, they enjoy an almost guaranteed windfall every year, from a US military budget worth roughly a trillion dollars. Hind Hassan travels to Washington to learn how these firms use their riches to buy influence – confronting the senators who receive hefty campaign donations from the industry, and hearing the tricks of the lobbying game from a former insider.